Frost Dates for 97875 — Stanfield, Oregon

Half of springs at Hermiston Municipal Airport, OR see their last 32°F night by April 26; only one in ten is past it by April 9, and one in ten still has one after May 10. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 6 20%, and after May 10 10%. The 14 days between the even-odds date and the one-in-ten date is the narrowest of the 103 Oregon stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 10 in half of years, as early as September 25 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 14 days later, around October 24; in spring the one-in-ten date for 28°F is April 29, 11 days before the 32°F one. The freeze-free season lasts 167 days in a typical year, shorter than at 72% of the 103 Oregon stations; it reaches 190 days one year in ten and falls short of 143 one year in ten. On average 115 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 12 days longer, to about May 8, and return around September 28. Severe cold of 16°F or below comes in 96% of winters, usually between December 5 and February 12.

July is the warmest month at Hermiston Municipal Airport, OR, averaging 93°F by day and 59°F at night; December is the coldest at 42°F and 28°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 34% of years.

Warmth for growing adds up to 3,173 growing degree days a year (base 50°F), more than at 97% of the 103 Oregon stations. 33% of them (1,034) have built up by the end of June, and July adds the most, 795. Precipitation totals 8.6 inches a year, most in January (1.1") and least in July (0.1"); May to September bring 23% of it.

The nearest other station, Hermiston 2 NW, OR, 7 miles northwest of Stanfield and 181 feet lower, has a last frost 1 day later (April 27), a first frost 3 days earlier (October 7), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Stanfield usually arrives around November 29, and the last of the season around March 1. Those are the middle dates across the winters of 1991–2020 at Pendleton, OR, 18.5 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 56 days after the last snow.

ZIP 97875 is 4 miles from Hermiston Municipal Airport, OR, which stands at 641 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 97875 in zone 7a, the band where the coldest night of the year averaged 0 to 5°F (-17.8 to -15.0°C) over 1991–2020; a zone describes winter lows, not frost dates.